Method:

1. Preheat the oven to 180°C.
2. Place 4 shallow 10cm tart pans or metal rings on a baking tray lined with baking paper and lightly brush with melted butter.
3. Place the walnuts, cinnamon and 1 tablespoon brown sugar in a mortar and pestle, and grind until you have fine crumbs. Set aside.
4. Cut the filo sheets into quarters to make 24 squares (keep the filo pastry covered with a damp tea towel while you work). Brush 3 filo squares with melted butter, then use the squares to line one of the tart pans, alternately positioning each layer at a 90° angle so that the pastry hangs over the edge of the pan.
5. Scatter 1 heaped tablespoon of the nut mixture over the pastry, then top with 3 more buttered filo squares positioned at angles as before. Repeat with remaining pastry, butter and nut mixture to make 4 tart cases.
6. Using scissors, trim the pastry leaving a 2cm border overhanging the tart pans. Bake for 10-12 minutes until just golden. Cool.
7. Meanwhile, combine the plums, star anise, orange zest and juice, and remaining 1 tablespoon sugar in a saucepan over medium heat. Cover and gently simmer, stirring, for 8 minutes or until plums are tender and starting to break down.
8. Check the sweetness and adjust with more sugar if necessary.
9. Dissolve the arrowroot or cornflour in 1 teaspoon water and add to the plums. Cook, stirring, for a further 2-3 minutes until slightly thickened. Allow to cool slightly.
10. Dissolve the arrowroot or cornflour in 1 teaspoon water and add to the plums. Cook, stirring, for a further 2-3 minutes until slightly thickened. Allow to cool slightly.
11. Gently unmould the pastry cases from the pans and place onto plates. Fill with the plum compote, dust with icing sugar and top with a dollop of creme fraiche and a sprig of mint.